How to Open the Cone to a larger voice coil opening:

Lay cone face down on table top
put top of voice coil onto voice coil opening of cone
use marker and drawer circle around outside of voice coil
(you can also mark the inside of the voice coil)
use a strait edge blade and cut cone inside the outer marked circle (if you marked inside and outside of voice coil, cut in between the two lines) be careful not to cut too large. it is easier to open the cone more if it is still too small.
use your thumb to gently smooth and enlarge the hole as needed
fit voice coil into new hole

Now that one cone is done you can use that cone as a template for the remaining cones and cut from that marking.

About Cathy Satin

Cathy is an expert in the field of speaker repair and technologies. She grew up in NY, moved to Florida in 1975 and graduated from the University of South Florida, with a degree in broadcasting. She and her husband Glenn started The Speaker Exchange in 1977. (Glenn later moved into Audio/Video sales and installations). In 1979, Cathy went to California for JBL speaker repair training and later received advanced training from Frank Spain, the then head of the Electro-Voice service department. She has continued to advance her audio education through many CES, NAMM, and CEDIA trade show classes.